First Time Leveling the Build Plate

[shdwsng]

When doing the initial leveling of the build plate, the instructions are fairly well written. However, if you don't get it right the first time it can be quite frustrating! As I have just found out from experience. So in order to help alleviate the pain, here's my tips for the initial calibration. 
 
Tip #1- When doing the initial leveling, the instructions call for using a single piece of A4 paper. According to the dimensions on that, it should be roughly 0.1 mm thick and theoretically should give you the right tension. However, when I zeroed my machine I started the initial Rook print and it hit bottom and started making a loud humming as if the motor was pressing against the screen when it shouldn't have been. To correct that problem, I took the piece of paper that I'd trimmed to fit and folded it in half. Zero the machine so that you can tug two sheets of paper free with very little drag and that cleared up the issue. 

Tip #2- If you need to re-level your print head if that happens then make sure you follow ALL the steps in the process. Starting with loosening the star bolts that hold the print head steady. The "zero" process presses the print head against the screen and then bottoms out on the springs holding up the build plate. If it doesn't have that "flex" then it will absolutely not let you get to the home point. And if you can't get to home, the system software won't let you reset the Z start point. So follow the steps in order: Loosen the screws. Slide the folded paper under the build plate. Get into Manual, and hit the house icon. Make sure the build plate is square with the screen. Tighten the front bolt and then the side bolt. Try to pull the paper out. Use the up and down arrows at 0.1 mm height in order to set it so the paper can be pulled free easily, but you feel a bit of friction when it's tugging against the build plate. Go back one screen, and hit the Set Z=0 button. 

I'm doing the initial print of the Rook test file now, but I wanted to get these impressions down while I was thinking about them. If the print is successful, I'll edit this to reflect that.

[mrjayd]

When doing the initial leveling of the build plate, the instructions are fairly well written. However, if you don't get it right the first time it can be quite frustrating! As I have just found out from experience. So in order to help alleviate the pain, here's my tips for the initial calibration. 
 
Tip #1- When doing the initial leveling, the instructions call for using a single piece of A4 paper. According to the dimensions on that, it should be roughly 0.1 mm thick and theoretically should give you the right tension. However, when I zeroed my machine I started the initial Rook print and it hit bottom and started making a loud humming as if the motor was pressing against the screen when it shouldn't have been. To correct that problem, I took the piece of paper that I'd trimmed to fit and folded it in half. Zero the machine so that you can tug two sheets of paper free with very little drag and that cleared up the issue. 

Tip #2- If you need to re-level your print head if that happens then make sure you follow ALL the steps in the process. Starting with loosening the star bolts that hold the print head steady. The "zero" process presses the print head against the screen and then bottoms out on the springs holding up the build plate. If it doesn't have that "flex" then it will absolutely not let you get to the home point. And if you can't get to home, the system software won't let you reset the Z start point. So follow the steps in order: Loosen the screws. Slide the folded paper under the build plate. Get into Manual, and hit the house icon. Make sure the build plate is square with the screen. Tighten the front bolt and then the side bolt. Try to pull the paper out. Use the up and down arrows at 0.1 mm height in order to set it so the paper can be pulled free easily, but you feel a bit of friction when it's tugging against the build plate. Go back one screen, and hit the Set Z=0 button. 

I'm doing the initial print of the Rook test file now, but I wanted to get these impressions down while I was thinking about them. If the print is successful, I'll edit this to reflect that.

I'm having the same problem with my new Mars Pro but I can't get anything to work. See my thread above called "New machine won't print". I've tried everything 10+ times and it just won't zero out with the Z=0 button.

[cliffyk]

First some illustrations, for clarity:

"Home" button:


"Z=0" button:


As I have stated in other posts:

• The mechanical alignment process; I.e. loosening lock screws, pressing the "Home" button, aligning the platen, etc.calibrates an absolute "zero" position determined by the optical limit switch;
  
  
• The "Z=0" function sets a logical "zero" position--a "zero" position related only to to the hardware "home" position by its offset from the absolute zero position;
  

The positions can coincide, and they do if the alignment process is carried out on it's own; however the trolley/platen can only be moved, and stopped at the logical zero position, by the firmware interpreting and acting upon G-Code positioning commands read from a file on the USB drive.

It is vital to understand that pressing the Home button will always send the trolley to the limit switch determined home position. Only G-Code commands will move it to the logical "zero" position, and that only after it has been moved to the hardware limit and then offset as required. 

There is no UI function to move the trolley to the "Z=0" set position.

They are separate and distinct functions/procedures...

[mrjayd]

First some illustrations, for clarity:

"Home" button:


"Z=0" button:


As I have stated in other posts:

• The mechanical alignment process; I.e. loosening lock screws, pressing the "Home" button, aligning the platen, etc.calibrates an absolute "zero" position determined by the optical limit switch;
  
  
• The "Z=0" function sets a logical "zero" position--a "zero" position related only to to the hardware "home" position by its offset from the absolute zero position;
  

The positions can coincide, and they do if the alignment process is carried out on it's own; however the trolley/platen can only be moved, and stopped at the logical zero position, by the firmware interpreting and acting upon G-Code positioning commands read from a file on the USB drive.

It is vital to understand that pressing the Home button will always send the trolley to the limit switch determined home position. Only G-Code commands will move it to the logical "zero" position, and that only after it has been moved to the hardware limit and then offset as required. 

There is no UI function to move the trolley to the "Z=0" set position.

They are separate and distinct functions/procedures...

Mine doesn't have those icons. My home button is just an outline of a house and my zero button is just again another outline of a house with Set Z=0 under it. And BTW, I just flashed the new code to enable the Z=0 function if it was indeed disabled but it just does the same thing. I see so many people having this same issue that I don't know whether to get a replacement or a refund. I have never had these issue with other brands.

[cliffyk]

I have had several email exchanges with Elegoo support (which BTW ha always been responsive and great to deal with) re; the "Z=0" function. Per them it has always been functional on any model that displayed the button. However (and this is my interpretation of our discussions) what it does--I.e. set a logical "zero" position only attainable through G-Code commands--is so subtle that it masy appear non-functional to those who do not understand what it does.

The most misunderstood part of it all is that the "Home" function will ALWAYS move the platen to the hardware limit switch determined "home" position regardless of how the logical "Z=0" position may have been set. There is no upper limit or linear position sensor--therefore all the machine knows about the current Z-axis position at any point in time is how many stepper motor "steps" it is away from the limit switch established absolute zero position.

Repositioning the trolley manually and setting the logical "zero" position stores, into non-volatile RAM, a value representing the current trolley position's number of "steps" away from the limit switch actual zero position. To go to that position with accuracy the firmware must first move the trolley to the limit switch extreme and then back upward by the stored value number of steps, to what we have told it is the "logical" zero position.

As I have said it is a very subtle function, that cannot be verified or observed via any UI command--it therefore "appears" disabled or non-functional to those who do not understand what it does. This, combined with that pressing the "Home" button will ALWAYS move the trolley to the limit switch controlled zero position, is what makes it seem ineffectual.